Merge branch 'hotfix/29'

Close #29

CHANGELOG.md

@@ -14,7 +14,9 @@ All notable changes to this project will be documented in this file, in reverse
 
 ### Removed
 
-- Nothing.
+- [#29](https://github.com/zendframework/zend-db/pull/29) removes the required
+  second argument to `Zend\Db\Predicate\Predicate::expression()`, allowing it to
+  be nullable, and mirroring the constructor of `Zend\Db\Predicate\Expression`.
 
 ### Fixed
 

src/Sql/Predicate/Predicate.php

@@ -242,7 +242,7 @@ public function notLike($identifier, $notLike)
      * @param $parameters
      * @return $this
      */
-    public function expression($expression, $parameters)
+    public function expression($expression, $parameters = null)
     {
         $this->addPredicate(
             new Expression($expression, $parameters),

test/Sql/Predicate/PredicateTest.php

@@ -229,6 +229,19 @@ public function testExpression()
         );
     }
 
+    /**
+     * @testdox Unit test: Test expression() allows null $parameters
+     */
+    public function testExpressionNullParameters()
+    {
+        $predicate = new Predicate;
+
+        $predicate->expression('foo = bar');
+        $predicates = $predicate->getPredicates();
+        $expression = $predicates[0][1];
+        $this->assertEquals([null], $expression->getParameters());
+    }
+
     /**
      * @testdox Unit test: Test literal() is chainable, returns proper values, and is backwards compatible with 2.0.*
      */